Sudden health problems such as sudden cardiac arrest and injuries caused by accidents kill thousands of people and cause permanent injury every year. Fast and competent care can be essential to positive outcomes in such situations. For example, it is said that the chance of surviving a sudden cardiac arrest falls by ten percent for every minute in delaying effective treatment.
Emergency events like sudden cardiac arrests and accidents are generally responded to by organized emergency response units, such as ambulance or fire crews, and by laypeople who are immediately around the events so that they personally witness or offer assistance for the events. Often, the laypeople in a victim's immediate vicinity are not trained to treat the victim, or are too overwhelmed to provide effective treatment. On the other hand, the organized emergency response units may be far away from the victim, so that they cannot arrive at the scene for a long time.